Does anyone know if a speaker for the v2-400 can be replaced and where to find a new one?  If not can it be fixed easily?  The right rear speaker has fallen off the stand one too many times and is no longer working.  I know that it is something with the speaker and hesitate to open it. 

you can buy a brand new replacement right from Klipsch, they are the exact same speakers that come with the ProMedia 2.1 systems. I have some extra ones here myself but I don't think I would just part with one, but I believe they are pretty cheap when you buy brand new from Klipsch. less than $30 each if I recall correctly.

4 philips screws.. pull it apart.  There is nothing that can go wrong..(it's not working at the moment anyhoo)

I have had mine open many time.  Just do not overtighten when you put it back together.  It may be a connection came apart inside from the jack to the driver or you might have a bad jack.  You can try connecting the driver direct to the amp to test or if you have a multimeter, you can test for continuity between the two ends of the wire at the amp end to the driver